Auto-pilot



Dec. 19, 1967 R. B. WALLACE 3,358,633

AUTO-PILOT Filed Feb. 21, 1966 2 Sheets-Sheet 1 72 VACUUM SUPPLY F|G.l

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VACUUM SUPPLY 94 8 l 56 I Y /70 INVENTOR. mo RD B. WALLACE ATTORNEYSDec- 19617 R. B. WALLACE 3,

AUTO-PILOT Filed Feb. 21, 1966 2 Sheets-Sheet 2 VACUUM SUPPLY H2 ooINVENTOR. RICHARD B. WALLACE FIG. 9 BY Z Z/ ATTORNEY United StatesPatent 3,358,633 AUTO-PILOT Richard B. Wallace, Bloomfield Hills, Mich.,assignor: to The Oakland Corporation, Troy, Mich., a corporation ofMichigan.

Filed Feb. 21, 1966, Ser. No. 528,723 15 Claims. (Cl. 114-144) ABSTRACTOF THE DISCLOSURE An auto-pilot for a boat responsive to roll or turningof the boat about its longitudinal axis to apply a rudder correction.

The present invention relates to an auto-pilot and more particularly, toan auto pilot responsive to roll or turning of a boat about alongitudinal axis to apply a rudder correction.

It is an object of the present invention to provide an automatic pilotincluding steering mechanism responsive to roll to operate the steeringmechanism.

It is a further object of the present invention to provide rollresponsive means in the form of a pendulum to apply a steeringcorrection to a boat in accordance with the magnitude and duration ofthe roll.

It is a further object of the present invention to provide an automaticpilot including fluid pressure means for operating a rudder includingvalve mechanism for controlling the fluid pressure means, the valvemechanism comprising a pair of independently movable valve elements,means responsive to roll of the boat for moving one of said valveelements, and means responsive to boat heading for moving the other ofthe valve elements.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating preferred embodiments of theinvention, wherein:

FIGURE 1 is a diagrammatic view illustrating one embodiment of thepresent invention.

FIGURE 2 is an enlarged fragmentary sectional view on the line 22,FIGURE 1 showing one valve position.

FIGURES 3 and 4 are enlarged fragmentary sectional views similar toFIGURE 2, showing different valve positions.

FIGURE 5 is a diagrammatic view showing a steering system which includesthe present invention.

FIGURE 6 is a diagrammatic view of a somewhat different embodiment ofthe present invention.

FIGURE 7 is an enlarged fragmentary view, partly in section, ofadjustable pendulum control means.

FIGURE 8 is an enlarged fragmentary sectional view looking in thedirection of the arrows 88, FIGURE 6.

FIGURE 9 is a diagrammatic view illustrating the provision of twodevices responsive to different conditions for controlling the positionof the rudder.

In prior Patent 3,148,654, in which I was a joint inventor, there isillustrated an automatic pilot intended primarily for use with smallboats. This automatic pilot under ideal conditions operates verysatisfactorily but use of this automatic pilot under varying conditionsdemonstrated that smaller boats could not be held closely to course inthe presence of certain wave actions. It is common knowledge thattypical power cruisers perform badly in a following or quartering sea,requiring a corrective turn of the boats wheel with each wave. While itappears superficially that only a boats rudder can cause a turn orchange in course, it has been found that whenever the boat rolls about alongitudinal axis, the hull in effect becomes a rudder. A roll to theleft without variaice tion in other factors produces a turn to the rightand vice-versa. The condition may be made worse, depending in part onhull design, by an off-setting action of the wave on the stern of theboat relative to the bow.

An investigation demonstrated to me that with a normal sea resultingfrom perhaps a 15 mile per hour wind, the piloting or course holdingproblem was created for the most part by wave action and only to a minordegree by changes in direction requiring a magnetically basedcorrection. It has been found that the wave-created factor risessteadily in direct proportion to wave size while it may reasonably beassumed that the magnetic course correction needs were substantiallyconstant.

An initial investigation of the problem was carried out with a pendulumactivated valve in control of fluid pressure (vacuum) power steeringmechanism. In practice, the pendulum actuated valve was substituted forthe compass control valve of the system shown in the prior Wallace etal. Patent 3,148,654 previously referred to. The results obtained wereastonishingly good. Even with no magnetic reference to the earths field,it was possible to hold a straight course for several minutes althoughthe wakes of other boats and regular waves were present tending to upsetthe original direction. Moreover, a roll of the boat occasioned by thelateral shifting of weight of two men, which would normally cause asubstantial turn, was cancelled completely by the counter-correction ofthe pendulum valve and the rudder correction which it applied.

The use of a pendulum controlled valve to counteract the tendency ofwave action to produce a change in correction is useful in reducing thesteering effort required by manual control of the rudder. In my priorcopending application Ser. No. 391,381, new Patent 3,263,639 I havedisclosed a steering system comprising an irreversible manuallycontrolled device such as a wheel operating through a worm and worm gearto apply longitudinal movement to an elongated telescoping motiontransmitting mechanism in association with power controlled means foreffecting changes in the effective length of the elongated member. Thepresent invention may be applied to control the mechanism for changingthe effective length of the elongated member in place of the compasscontrolled mechanism illustrated in the copending application.

The most useful applicaton of the present invention however,contemplates the combination of course sensitive means including acompass such for example as a magnetic compass, and a roll responsivemeans such as a pendulum, together actuating a single valve mechanismfor effecting automatic steering of a boat or automatic means forassisting manual steering of the boat.

Referring first to FIGURE 1 there is illustrated a mounting plate 10 towhich is pivoted an assembly subplate 12, the pivot connection beingillustrated at 14. Formed on the assembly sub-plate 1 2 is a bossforming a valve base 16 having valve ports therein as will subsequentlybe described. Pivoted to the valve base 16 'by a pivot connection 18 isa valve plate 20. Spring biasing means indicated generally at 20a areprovided holding the valve plate 20 in sealing relation against the flatsurface of the valve base. Details of the spring biasing means may bethe same as illustrated and described in detail in connection with asecond embodiment of the present invention.

Also pivoted to the assembly sub-plate 12 at 21 is a pendulum '22including a pendulum weight 24. The pendulum includes a valve actuatingarm 26 having a round head 27 received in the space between a pair offurcations 28 provided at the lower end of the valve plate 20.

The coaction between the valve structure incorporated in the valve base16 and the valve plate 20 may be of different types depending on thetype of power mechanism for shifting the rudder. In the present case theroll responsive mechanism is connected to a system as best illustratedin FIGURE 5, in which a boat rudder 30 is connected to be operated by amanually rotatable wheel 32 through suitable irreversible drivemechanism such for example as a worm and worm wheel which may becontained in a transmission housing 34. The connections between thetransmission housing 34 and the rudder include elongated motiontransmitting mechanism indicated generally at 36 which may take the formof rod means including a pair of telescoping rod sections 38 and 40.Means are provided for effecting relative longitudinal movement betweenthe rod sections 38 and 40 and this means comprises a lever 42 pivotedat 44 on a bracket 46 connected to a tubular sleeve 48 carried by therod section 38. The lever 42 has a motion transmitting connection 50with the rod section 40. It will be understood that the tubular sleeve48 is movable with the rod section 38 and in the absence of swingingmovement of the lever 42 about its pivot 44, the sleeve, bracket andlever all move in unison with the rod sections '38 and 40.

Power actuated means for the lever 42 is provided and takes the form ofa fluid motor such as the expansible bellows 52 having a tension spring54 tending to move the bellows to open position against a controlledvacuum admitted through a vacuum supply line 56. The bellows includes amovable wall 58 to which the spring is connected and which also isconnected to a rod 60 extending into one end of a flexible bowden wiredevice indicated generally at 62. The opposite end of the bowden wiredevice is connected to the bracket 46 and the flexible wire therein isconnected to a rod 64 which in turn is connected to the lever 42.Accordingly, as the degree of vacuum in the bellows 52 is varied,movement of the wall 58 results in swinging of the lever 42 andcorresponding movement of the rod section 40- relative to the rodsection 38, thus resulting in a change in the effective length of theelongated motion transmitting mechanism 36 connecting the transmissionhousing 34 to the rudder 30. The roll sensitive valve mechanismdescribed in connection with FIGURE 1 includes the valving structurebest illustrated in FIGURES 2, 3 and 4. The valve base 16, as best seenin FIGURES 2 and 3, is provided with a pair of ports 66 and 68. The port66 maybe formed by the end of the tube or conduit 56 which appliesvacuum to the bellows 52 as previously described. The tube or conduit 70extends to a vacuum supply structure 72 which may be the manifold of anengine on the boat.

The valve plate 20 is provided with an elongated recess 74 which in theposition of parts shown in FIGURE 2, affords connection between thepassages formed by the tubes or conduits 56 and 70. The valve plate 20is further provided with a through opening 76 which is adapted toregister with the port 66 formed at the end of thetube or conduit 56 soas to vent the interior of the bellows 52 to atmosphere when the partsare in the position shown in FIGURE 4. The valve occupies the positionillustrated in FIGURE 3 when the boat is in a normal position. In thisposition it will be observed that the recess 74 connects the port 68 tothe port 66 but the port 66 is also in limited communication with theopening or passage 76. Accordingly, the vacuum supply conduit 56 is bledto atmosphere an amount depending upon the exact position of the valveplate 20 relative to the valve base 16. At this time the eifectivenessof the partially bled vacuum suppliedto the bellows 52 is sufiicient tomaintain the bellows in an intermediate position against the bias of'thespring '4 so as to maintain the rudder 30 amidships when the wheel 32 isin the amidships position.

If the boat rolls to port the pendulum remains in a veritical positionand the valve plate 20 is swung in a counterclockwise direction as seenin FIGURE 1, or toward the limiting position shown in FIGURE 4. At thistime the vacuum supply conduit 56 is in full communication with thebleed opening 76 and the vacuum port 68 is means 36. Assuming themanually operated wheel 32 is stationary at this time, this will resultin a movement of the rudder to port sufficient to overcome the tendencyinduced by the wave action and resulting roll of the boat to cause theboat to change course.

Conversely, if the wave action causes roll of the boat to starboard thevalve plate 20 is shifted from the intermediate position illustrated inFIGURE 3 toward the limiting position illustrated in FIGURE 2 whicheliminates the atmosphere bleed to the vacuum supply conduit 56, andwhich affords unrestricted communication between the vacuum tube 70 andthe vacuum supply line 56 connected to the bellows.

When the boat regains an even keelfollowing the roll induced by waveaction, the valve plate 20 resumes the intermediate position shown inFIGURE 3 and the rudder returns amidships due to the water pressure onthe rudder and leakage inthe system, the position of the valve plate 20being suflicient to supply a partially bleed vacuum to balance the forceexerted by the spring 54.

It is of course within the contemplation of the present invention toprovide a valve port 66 which is elongated along the line connecting itto the port 68 so as to facilitate balancing of the vacuum in thebellows against reaction forces developed on the rudder and the actionof the spring 54.

Means are provided for restricting movement of the pendulum 22 relativeto the sub-plate 12 and this means constitutes abutment screws 80extending through ears 82 provided on the sub-plate 12. By this means,move ment of the valve plate 20 beyond predetermined limiting positionsis avoided.

The foregoing construction provides mechanism for effecting automaticadjustment of the rudder to anticipate and prevent changes in directionresulting from wave action and/or tilting of the boat. When employed ina system as illustrated in FIGURE 5, the-roll responsive auto-pilot iseffective to eliminate a major portion of the steering effort requiredby the boat operator. How ever, it still requires the atention of theoperator to maintain the boat on its true course over a substantialperiod of time. The present invention is however particularly welladapted to combine with course sensitive means to completely eliminatethe necessity for attending the wheel.

As previously noted, the sub-plate, 12 is pivoted to the mounting plate10 and swinging movement of the subplate 12 about the axis of pivot 14is accomplished in response to changes in course. For this purpose asecond bellows 82 is mounted on the mounting plate and includes apivoted wall 84 connected by a link 86 to the sub-plate 12. The movablewall 84 is also connected to a tension spring 88 the oppositejend ofwhich is suitably connected to a fixed spring support on the mountingplate 10. The interior of the bellows 82 is connected by a vacuumpassage 90 to the vacuum supply source 72 through a restriction in thepassage indicated at 92. The passage 90 includes a bleed valve indicatedgenerally at 94 which is responsive to departures from a preset headingand includes a compass controlled valve element which may be of the typedisclosed in prior Wallace et al. Patent 3,148,654. Accordingly, avacuum, the degree of which is determined by changes in the boatheading, is applied to the bellows and is efiective' when the boat is oncourse to maintain the sub-plate 12 in its in termediate position.

It is of course evident from an inspection of FIG- URES 1-4 that thevalve action may be obtained by movement of the valve plate 20 over thevalve base 16 or alternatively, by movement of the valve base relativeto the valve plate. Of course, it is possible for a change in course androlling action of the boat to cause independent movement of the valvebase and valve plate and these independent movements may be in the samedirection or in opposite directions. In any case, movement of thesub-plate 12 in accordance with departures from preset course applies arudder correction dependent upon the magnitude of the course change andin a direction tending to restore the boat to its true course.

Inasmuch as the transmission connecting the wheel 32 to the rudder 30 isirreversible, it is possible for the boat operator to bring the boatonto a desired course by appropriate manipulation of the wheel and tohold it on this course by appropriate adjustment of the rudder to therequired position, which may or may not be strictly amidships. Then ifthe full auto-pilot system is connected in, the operator may release thewheel which remains in its last position, and the auto-pilot takes overcompletely, providing the repeated rudder corrections required toeliminate course changes due to roll and to provide the necessarychanges in average rudder position as required to maintain the truecourse.

Referring now to FIGURES 68 a somewhat different embodiment of theinvention is illustrated which however, operates on precisely the sametheory. In this embodiment of the invention the mounting plate isindicated at 100 and the sub-plate 102 is pivoted thereto by a pivotmounting indicated at 104. In this case the valve plate 106 is pivotedon the same pivot mounting 104 as the sub-plate and hence it remains inundisturbed position when the sub-plate is tilted or pivoted inaccordance with changes in course. A pendulum 108 is pivoted directly tothe mounting plate 100 by pivot means 110 which extend through anopening 112 provided in the sub-plate 102. Thus, tilting of the subplate102 in response to changes in course does not atfect the pendulum.

While valve means identical with those described in connection withFIGURES 1-4 may be provided in the embodiment of the inventionillustrated in FIGURE 6, in this figure there is illustrated aspecifically different arrangement in which a pair of valve parts 114and 116 are provided at the upper surface of the sub-plate 102 and arepartially and equally closed by the valve plate 106 when it is in itsintermediate position as illustrated in the figure. A rudder indicatedgenerally at 118 is pivoted as indicated at 120 and has fixed thereto apair of walls 122 and 124 each of which cooperates with a fixedintermediate wall 126 to provide two opposed expansible and contractablebellows chambers as illustrated.

A vacuum supply 128 which may be the manifold of the internal combustionengine on the boat, is connected through restrictions indicated at 130by a conduit 132 to the chamber intermediate the walls 124 and 126, andby the conduit 134 to the chamber intermediate the walls 122 and 126.

The bleed port 114 is connected by a conduit 136 to the vacuum conduit134 and the bleed port 116 is connected by a conduit 138 to the vacuumsupply conduit 132.

With the parts in the position illustrated in FIGURE 6, and with thebleed ports 114 and 116 partially but equally restricted, it will beapparent that the vacuum provided to the interior of the chambersintermediate the walls 122, 126 and 124, 126, is equal and accordinglythe rudder will remain in intermediate position and move to theintermediate position if displaced from intermediate position when thevalve plate 106 returns to the illustrated position.

As before, the sub-plate 102 is adapted to be pivoted from theillustrated intermediate position about the pivot axis 104 in accordancewith changes in course from a preset heading as controlled by a bleedvalve indicated diagrammatically at 140 in the vacuum supply line 142 6connecting the vacuum supply 128 and a bellows 144. The bellows includesa fixed wall 146 and a movable Wall 143 connected by a link 150 to thesub-plate 102. The movable wall 148 of the bellows is connected by atension spring 152 to the mounting plate 100. With this arrangement thesub-plate 102 will be maintained in an intermediate position when thecompass controlled bleed valve 140 is maintained in a positioncorresponding to the desired heading. Upon a change in heading in eitherdirection, the effectiveness of the bleed valve is either increased ordecreased, thus correspondingly increasing or decreasing the degree ofvacuum in the bellows and resulting in a corresponding shift in thesubplate to a position in which the tension of the spring 152 iseffective to counterbalance the changed vacuum.

The sub-plate 102 is provided with ears 154 carrying adjustable abutmentscrews 156 so that swinging movement of the pendulum 108 relative to thesub-plate 102, and accordingly movement of the valve plate 106 relativeto the sub-plate, is maintained between predetermined limits. Inaddition, the mounting plate 100 is provided with ears 158 carrying setscrews 160 adapted to engage the edges of the sub-plate 102 andadditional set screws -162 adapted to engage the pendulum 108. With thisarrangement set screws 160 may be set to limit swinging movement of thesub-plate 102, or they may be advanced to prevent movement of the plate,in which case the device is responsive only to roll and will require theattention of the boat operator to maintain the boat on true course overprotracted periods. On the other hand, if the set screws 162 areadvanced to engage the pendulum, the roll sensitive piloting action iseliminated and only the compass responsive piloting action ismaintained.

The provision of the abutment screws 162 for immobilizing the pendulummay be considered as illustrative only of any suitable means forpreventing operation of the auto-pilot system in response to roll orlisting of the boat. Obviously, similar results may be accomplished bythe provision of valves in the vacuum supply lines leading to the valveports 114 and 116. Similarly, the compass controlled system may ofcourse be selectively disalzled by operation of a valve in the vacuumsupply line 1 2.

Referring now to FIGURE 7 there is illustrated adjustable meansconnected to the pendulum as by an extension '164 comprising a pair ofrelatively large light pistons 166 movable with considerable freedom incylinders 168 having small axial extent and having a relatively largeopening 170 adapted to be closed by a swinging valve element 172 pivotedfor example as at 174 and having a manipulating finger piece 176. Thepistons 166 constitute dashpot mechanism effective to modify andsomewhat slow the action of the pendulum 108 as the boat rolls.

Referring now to FIGURE 8, mechanism for maintaining the valve plates 20or 106 in firm position against the ported valve base surfaces isillustrated. In this figure the valve plate 106 is shown as connected bythe pivot 104 which serves as a common pivot for the sub-plate 102 andthe valve plate 106 and the mounting plate 100. The valve plate 106 mustswing freely and freedom must be provided for independent swinging ofthe sub-plate 102, but at the same time it is essential for the abuttingsurfaces of the sub-plate and valve plate to maintain firm contact.Accordingly, a screw is threaded into a tapped recess 182 in thesub-plate 102 and extends through an enlarged opening in the valve plate106. A washer 184 is provided and interposed between the washer and thehead of the screw 180 is a resilient washer or spring device 186 adaptedto maintain a light but constant pressure contact between the abuttingsurfaces of the sub-plate 102 and the valve plate 106.

While in the foregoing reference has been made to a rudder correction,or movement responsive to roll, or movement of the boat about alongitudinal axis, it is sometimes desirable to provide independentsubstantially similar devices one of which is responsive to periodicroll as induced by a more or less regular succession of waves, and theother of which may be induced by listing of the boat which remains in acanted or listing position for a substantial interval.

In FIGURE 9 such a system is diagrammatically illustrated and comprisesa wheel 19% connected to a rudder 191 through elongated motiontransmitting means 192. Diagramrnatically indicated at 193 is themechanism responsive to periodic rolling motion of the boat foreffecting correction by shortening and lengthening the elongated motiontransmitting means, the details of which are clearly illustrated inFIGURE and have been described at length in the foregoing. Intermediatethe roll responsive mechanism for shortening the length of the elongatedmotion transmitting means 192 is a second similar device 194 which maybe identical in all respects except that the pendulum of the type shownat 22 in FIG- URE 5 is heavily damped as for example by dashpot means ofthe type illustrated in FIGURE 7 but differing specifically therefrom inthat the fluid displaced by move ment of the pistons is preferably inthe form of a hydrau lic fluid displaceable through relativelyrestricted passages. Thus, the pendulum associated with the mechanism194 will not be significantly responsive to back and forth roll but willinstead be responsive to a listing of the boat which is maintained for asubstantial interval, for example 30 seconds or a minute, or more. Thisdevice will also of course be responsive to the average list so that thefact that the'boat, in addition to listing, is subjected to a rollingmotion, will not prevent the list responsive mechanism from operating.

A prime advantage of the use of the two mechanisms, one of which isresponsive to fairly rapidlyrecurring rolling motion and the other ofwhich is responsive to list or average list, is that the range ofcontrol provided by the roll responsive mechanism is not restricted andthe total control is the additive result of the control exerted by theroll responsive mechanism and by the list or average list responsivemechanism.

Attention is called to the essentially modular construction of both ofthe embodiments of the invention previously described. It. is possibleto install the auto-pilot mechanism responsive solely to rolling of theboat without obtaining the compass control mechanism although thepivoted sub-plate used in connection with the compass controllcdauto-pilot mechanism will be present. The roll controlled auto-pilotwill then function as described, eliminating the major portion of theeffort required by the helmsman to overcome the wave action normallyshifting the boat off course. At any future time it is then a simplematter to add the compass controlled part of the mechanism by simplyconnecting the bellows device associated therewith to the sub-plate andconnecting it to the compass modifying source of vacuum.

The drawings and the foregoing specification constitute a description ofthe improved auto-pilot in such full, clear, concise and exact terms asto enable any person skilled in the art to practice the invention, thescope of which is indicated by the appended claims.

What I claim as my invention is:

1. An auto-pilot system for a boat having a rudder including a powerdevice for moving the rudder, means responsive to roll or movement ofthe boat about a longitudinal axis for operating the power device.

2. An auto-pilot system as defined in claim 1 in which the meansresponsive to roll or tilting of the boat about a longitudinal axiscomprises a pendulum.

3. An auto-pilot system as defined in claim 2 in which the power deviceis a fluid pressure operated device, valve means for controlling thedevice, and means connecting said pendulum to said valve means.

4. An auto-pilot system as defined in claim 3 in which said power deviceis vacuum operated, and in which said valve means comprises one or moreatmosphere bleed valves.

5. An auto-pilot system as defined in claim 21 comprising means forlimiting the amount of movement of thependulum from intermediateposition.

6. An auto-pilot systemas defined in claim 2 comprising means forcontrolling the rate of response of the pendulum to roll or tilting ofthe boat about a longitudinal axis.

7. An auto-pilot system as defined in claim 1 comprising in additionmeans responsive to departure of the boat from a preset course foroperating the, device in a direc-. tion to restore the boat to thepreset course.

8. An auto-pilot system for a boat as defined in claim 7 which comprisesa pair of cooperating valve members, means responsive to roll or tiltingof the boat about a longitudinal axis for shifting one of said members,means responsive to variations in course to shift the other of saidmembers, the course responsive means being separable from andselectively applicable to the valve member adapted to be controlledthereby, whereby the course responsive part of the system is an optionwhich may be added to the roll responsive system at any time.

9. An auto-pilot system as defined in claim 7 in which the power deviceis a fluid operated. motor, valve means in control of the motor, saidvalve means comprising first and second independently movablecooperating valve members, means connecting one of said valve members tothe means responsive to roll or tilting of the boat about a longitudinalaxis, and. means connecting the other of said valve members to the meansresponsive to departure of the boat from a preset course.

10. An auto-pilot system as defined in claim 9 in which the meansresponsive to roll or tilting of the boat about a longitudinal axiscomprises a pendulum, and means connecting said pendulum to one of saidvalve members.

11. An auto-pilot system as defined in claim 9 comprising means forselectively disabling the means responsive to roll or tilting of theboat about a longitudinalaxis and the means responsive to departure ofthe boat from a preset course to provide for operation of the steeringmechanism in response solely to departure of the boat from a presetcourse or solely to roll or tilting of the boat about a longitudinalaxis, or jointly in response to both roll or tilting of the boat about alongitudinal axis and departure of the boat from a preset course.

12. An auto-pilot system for a boat having a rudder, a wheel, elongatedmotion transmitting means interposed between the rudder and wheel, and aone-Way driving connection from the wheel to the motion transmittingmeans, means for effecting variations in length of the motiontransmitting means so as to produce movement of the rudder independentof or in the absence of movement of the wheel, power means for producingeffective changes in length of the motion transmitting means, and meansresponsive to roll or tilting of the boat about a longitudinal axis tocontrol operation of said power means to effect changes in the effectivelength of said motion transmitting means.

13. Apparatus as defined in claim 12 comprising in addition meansresponsive to departure of the boat from a preset course to effectchanges in the length of the motion transmitting means, the meansresponsive to departure of the boat from a preset course being operablesimultaneously with the operation of the means responsive to roll ortilting of the boat about a longitudinal axis so as to producevariations in the length of the motion transmitting means dependentjointly on roll or tilting of the boat about a longitudinal axis anddeparture of the boat from a preset course. i

14. Apparatus as defined in claim 13 comprising means for disabling themeans responsive to roll or tilt- 15. Apparatus as defined in claim 12in which the eifective change in the efiective length of the motionmeans responsive to roll or tilting of the boat about a transmittingmeanslongitudinal axis is responsive essentially to rolling mo-References Cited tron repeated at relatively short intervals, 1n eombmaton 5 UNITED STATES PATENTS with a second power means for producingaddltlve 176 8 7 10/1939 W h 114 144 h h h r t 'ttin 3135 gigs t o lisfin Z; a ve rZ i l istin 3 t l 1 ei b a 1 2498223 2/1950 Rommel 114144S P g g g 3,263,639 8/1966 Wallace 114 144 to control the operation ofthe second power means to efiect with the first mentioned power means anoverall 10 ANDREW H. FARRELL, Primary Examiner.

1. AN AUTO-PILOT SYSTEM FOR A BOAT HAVING A RUDDER INCLUDING A POWERDEVICE FOR MOVING THE RUDDER, MEANS RESPONSIVE TO ROLL OR MOVEMENT OFTHE BOAT ABOUT A LONGITUDINAL AXIS FOR OPERATING THE POWER DEVICE.